Butterfly Time in the Lower Rio Grande Valley

Last year we had such a good time in the Lower Rio Grande Valley of Texas in late October/early November (you can read about it here and here) that we decided to go again, adding a few more days on to the trip. At this time of year, butterfly abundance in the Valley is at its maximum, and there is always the chance for a rare Mexican stray. The Texas Butterfly Festival (November 1-4), headquartered at the National Butterfly Center in Mission, hosts lots of excellent programs and tours which attract outstanding guides and participants from all over the country. 

We used our time to explore a lot on our own and also enjoyed attending some of the festival events. We ended up seeing about 115 different species of butterflies, lots of birds and other interesting animals, and basically had a great time. I won't bore readers with lists of all that we saw, but some of the many highlights are worth describing!

In the weeks leading up to our trip, we read about lots of interesting butterfly sightings on the "Rio Grande Valley Butterflies" Facebook site. One was especially tantalizing, a gorgeous critter called the Two-barred Flasher. We figured that it would be gone before we got down there, but they kept turning up in various parks and gardens so we thought we had a chance. 

One of our first stops in the Valley that had reported the flasher was Estero Llano Grande State Park, one of our favorite birding and butterflying destinations. Of course, as soon as we pulled into the parking lot a handful of people told us that it had just been seen a few minutes ago, but had since disappeared. A half dozen of us looked for at least 45 minutes with no luck. Bill and I wandered around some other parts of the park, until I decided it was getting late and that we had better check into our hotel. Bill is persistent about these things, though, and suggested another look at the lush flowering shrubs around the parking lot. We rounded a corner and there it was!

This spectacular insect is even more stunning in person, with its iridescent blue back and white stripes against a dark background. While we saw several Two-barred Flashers during our trip, this was the freshest. At one point, not six inches away was another spectacular butterfly, the Guava Skipper:

Wow--what a great way to start!

Some butterflies are rare because their preferred habitat is restricted in the US. Such is the case for the Xami Hairstreak, a tiny green creature whose caterpillar requires succulent host plants that only grow in arid scrub habitats. Many are found in remote areas that require trekking through a cactus-studded landscape. We had a good tip about a promising area, so we joined up with a fellow butterflier, Steve from New Jersey, to see if we could find it. Within about 5 minutes I spotted one in a patch of its host plant, right by the dirt road! 

All three of us managed to get photos; none of us had ever seen this beautiful butterfly before. 

Buoyed by that successful stop, we headed to nearby Palo Alto National Historical Site, which preserves the location of a battle between the United States and Mexico in 1846. For years it has also been a fairly reliable location for a rare butterfly called the Definite Patch. We have tried to find it a couple of times in past visits but were never successful. This time, I spotted one near the visitor center pretty quickly but before I could really look at it off it went up and over a tall fence. Fortunately, soon after that Bill called out that he had one right in the center's garden and it was quite cooperative. 

Another popular area for both butterfliers and birders is the Frontera Audubon Center in Weslaco. It isn't one of my favorite places, probably because one area is a roosting site for lots of turkey vultures and that area can get pretty disgusting. A gorgeous butterfly called the Crimson Patch was reported to be there in good numbers, though, so it was definitely worth a visit. We spotted some before we were out of the parking lot! They basically were never still, so I had to set my camera to burst mode to get decent shots:

On Sunday we attended one of the festival programs at the National Butterfly Center, an all day session aimed at improving identification skills for some of the more confusing groups of butterflies. The leaders presented very helpful slides and then we went out into the center's extensive gardens to practice identification. Word of a sighting of an extremely rare butterfly came in from one of the festival's tour groups, from a site about 25 minutes west. When we had the chance we headed out there and joined several other people who were looking for this rare Mexican stray, the Blue-studded Skipper. We had spent about 3 hours at the same spot the day before and had about 30 different species but nothing unusual. Even with several observers, we were unable to find it.

The next morning we were planning a trip to Falcon State Park, and the Blue-studded Skipper site was on the way so we decided to give it another try. Steve from New Jersey was there too. Bill and I stood at the spot where it had been reported the day before, and after about 10 minutes I noticed a dark spot on a leaf and checked it out with my binoculars. There it was! I grabbed Bill's arm, tried to explain which leaf to look at, took some pictures and texted Steve who was around the corner. We all got photos--what a cool-looking bug! 

It looked like fine iridescent blue glitter had been sprinkled on this butterfly. Two vans of people from the festival were pulling into the parking lot as we were leaving, but as far as I know the Blue-studded Skipper was not spotted again. Once again, persistence paid off for us.

On we went to Falcon State Park, which reportedly had huge quantities of butterflies in the garden there. That seemed likely to be an exaggeration, but it most definitely was not. There were literally thousands of butterflies of all shapes and sizes bouncing around the flowers, and with each strong gust of wind it looked like handfuls of confetti had been tossed into the air. My favorite was the tiny Lantana Scrub-hairstreak:

This and many others were so intent on feeding that I could get within an inch of them and use the macro setting on my camera! Among many other species there were hundreds of Queens,

probably thousands of tiny blues including this Reakirt's Blue,

a few Zilpa Longtails with their great camouflage,

an Erickson's skipper,

and nearby, thanks to tips from Florida friends, we found this lovely tiny Red-crescent Scrub-hairstreak:

Our last day in the Valley didn't look too promising, with heavy clouds and intermittent rain. We decided to try the weekly butterfly walk at Santa Ana National Wildlife Refuge despite the weather. It was raining as we got out of the car, but we noticed leader Mike Rickard and a refuge employee looking intently at something on one of the pillars of the visitor's center. As we got closer we saw that it was an incredibly huge moth, at least 5 inches across! 

This was an Owl Moth (Thysania zenobia), which we had never seen before. It stood out prominently on the white pillar but just think how well camouflaged it would be perched against a tree trunk. And I may never get over the perfect beauty of that scalloped border--what an amazing insect!

Despite the rain we had a good walk with Mike and enjoyed seeing the butterflies pop out to get a bit of nectar whenever the sun came out. We saw another Two-barred Flasher and got good looks at this green kingfisher:

From there we headed back to Estero Llano Grande State Park, delaying our departure for Corpus Christi and our Thursday morning flight as long as possible. We found a dry picnic table by the parking lot and got out our lunch. A group from the Rio Grande Valley Birding Festival, a huge event based in Harlingen, was returning to their van after checking out the birds in the park. 

One of their leaders, Dan Jones, was a leader for our butterfly festival seminar/tour and came over to say hello. He looked aside at a flowering shrub next to our table, yelled "Tailed Aguna" and ran to the van for his camera! In mid-sentence and with no binoculars he correctly identified this extremely rare butterfly that he had never seen before--amazing!

We got pictures, I texted a couple visiting from Florida who I knew would be interested, and the birding group came over to see what all the fuss was about. The aguna flew up into a small tree and their other leader, author and birding guide Jon Dunn, got a spotting scope on it so all could see it. I don't know if we converted any of the birders into butterfliers but it was fun to see so many people enjoying this unusual insect!

Soon several other butterfliers arrived to admire the Tailed Aguna, which came back down to nectar on the flowering shrubs. It was even a new butterfly for park naturalist and former Ohioan John Yochum. 

Finally we had to head to Corpus Christi, after a fun and satisfying stay in the Rio Grande Valley. Not only were the butterflies outstanding, but so were the guides and organizers of the butterfly festival and all of the other Valley residents and visitors with whom we shared sightings and friendship! 

Scissor-tailed flycatcher looking a bit askance at the birders and butterfliers
in the Estero Llano Grande State Park parking lot